Narrowing searches based on url, author, date, and other attributes is also possible. For instance, the query [ Streisand sourcename:Techdirt ] restricts searches for "Streisand" to items from the blog "Techdirt".
Examples of other operators follow:

sourceurl:http://www.theverge.com/

items from the blog http://www.theverge.com/

sourcename:"New York"

items from blogs with "New York" in the name

date:10/20/11

items that appeared on 10/20/11

date:[10/1/11 TO 10/20/11]

items appearing between 10/1/11 and 10/20/11

author:"Bill Gates"

items by author "Bill Gates"

title:unsubstantiated

items with "unsubstantiated" in the title

body:"severely polluted"

items with "severely polluted" in the body

link:http://www.marco.org/2011/04/16/rumored-apple-hdtv

items linking to http://www.marco.org/2011/04/16/rumored-apple-hdtv

Note: all operators that take urls will accept simple domain names, which match any item at that domain, or complete item urls.

Why I'm interested in Bitcoin
— Some people assume that all Bitcoin advocates are motivated by a libertarian political agenda. That is certainly not my agenda. I'm a lifelong Democrat who supported Obama in the last two elections. I think the Federal Reserve plays an important function …

Coinbase
— One of the interesting things about Bitcoin is the contrast between how it is portrayed in the press and how it is understood by technologists. The press tends to portray Bitcoin as either a speculative bubble or a scheme for supporting criminal activity.

Some thoughts on startup crowdfunding
— Like a lot of people, I'm excited about crowdfunding, and specifically the crowdfunding of startups now that's it's legal in the US. Based on my own experience investing in startups, here are some thoughts and issues that come to mind regarding startup crowdfunding.

The idea maze
— The pop culture view of startups is that they're all about coming up with a great product idea. After the eureka moment, the outcome is preordained. This neglects the years of toil that entrepreneurs endure, and also the fact that the vast majority of startups change over time, often dramatically.

Some thoughts on mobile
— People tend to lump smartphones and tablets together as “mobile”. This can be misleading. Ask people who run internet companies and they'll tell you that user behavior on tablets is far more similar to user behavior on desktops/laptops than it is to user behavior on smartphones.

The computing deployment phase
— Technological revolutions happen in two main phases: the installation phase and the deployment phase. Here's a chart (from this excellent book by Carlota Perez via Fred Wilson) showing the four previous technological revolutions and the first part of the current one:

Samsung's predicament
— In the past year, Samsung went from being a moderately successful electronics manufacturer to the leading non-iOS mobile device maker. Together, Apple and Samsung earn 98% of the profits in the smartphone market. MG Siegler echoed a common sentiment when he wrote …

The product lens
— There has been a lot of discussion lately about the markets for startup financing. Many of the discussions use words like “valuations” “bubble” “crunch” etc. Words like that generally mean the writer is discussing the world through the lens of finance.